My Giant Halfway is wobbling at the hinge. Not nice to ride and once this starts it only gets worse. There is a video on YouTube on repairing this, but the information there is incomplete so I thought this might be useful to share.

First step is to separate the two halves of the frame. This means removing the gear and rear brake cables before removing the pin. Not too hard, especially if you are going to replace the cables which is something you’ll almost certainly need to do anyway.

Getting the bushings out is the big problem. The inner bushings pulled out by inserting an 8mm tap and pulling – this is probably where the wear is – around the bushings in the frame rather than the pin. Anyway, easy.

The outer bushings were harder. The hole is 8mm so the 8mm tap I’d used for the inner bushings didn’t have any grip. I suspected a 10mm tap might be too big (correctly as it turned out) so I dug through my UNF taps and found a 3/8″ tap. I also managed to find a matching bolt. 3/8″ is 9.525mm so about the right size.

I carefully tapped the bushing and inserted the bolt. Wiggled it – nothing. Hit it with a small hammer – nothing. Medium hammer – nothing. I would normally put a socket over the bush flange and pull it out by tightening a bolt but the flange covers the area I’d need to push on. Tried the biggest hammer – finally movement! Hooray!

So they are all out. They are marked 0808F and appear to be a split flanged bronze bush. Drawing is below – measurements are approximate so don’t expect these values to work for your bike. However they may give you a starting point.

I’m trying to find a supplier for these. Failing that I’ll have to make some.

Update 16 May 2024:

I haven’t managed to find a supplier for the bearings. Giant don’t stock them and a local bearing shop don’t either.

I’ve tried making my own out of brass as in the YouTube video.

The first one came out ok – it is a good tight fit into the bike and there isn’t too much play around the pin. However all I’ve been able to do since then is make the pin hole too big, destroying expensive brass. I need to work out a better way to get the pin hole the right size – probably by making a stepped or tapered plug gauge.

Update 12 September 2024:

Finally got this done. Hardest machining job I’ve ever done.

Background – the pin is very slightly less than 8mm diameter. I assume that this is so when the bushes are pressed into the frame and they shrink, the pin is the correct diameter. It is about 0.04-0.06mm smaller than 8mm. Making the hole 8mm means too much play.

Measuring a hole this accurately is very hard. It isn’t possible to do this with the pin as the hole is too small then too big. The only practical way is to make a gauge, tapering the end so I could get an idea when the hole was almost the right size. Using this I managed to make a bush correctly. Horray! Then extra complications kick in…

First, most of the play was from one of the holes in the frame being worn oversize. I drilled this one out very slightly to 10.2mm – most are 10.1mm ish. However, this new hole wasn’t perfectly lined up with the hole on the other side of the frame so the pin didn’t go through.

Second, the bushes close up slightly when pushed into the frame.

The only way to make this work was to make a reamer. I extended my gauge a bit and cut grooves into the side by running the lathe tool along the workpiece with the spindle off. Not a great cutting tool and not hardened but ok for brass.

Once I had the reamer it all went together ok (i.e. with a rawhide hammer and swearing). However there is absolutely no play at all and the bike now rides properly.

If you want to do this job you need to either:

• Make a reamer – hopefully a better one than mine, or
• Buy a new pin of 8mm diameter and a reamer to match.